<template>
  <div>
    <router-link
      tag="div"
      to='/'
      class="header-abs"
      v-show="showAbs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed"
         v-show="!showAbs"
         :style="opacityStyle"
    >
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
  export default {
    name:'DetailHeader',
    data: function () {
      return{
        showAbs: true,
        opacityStyle: {
          opacity: 0
        }
      }
    },
    activated() {
      window.addEventListener("scroll",this.handleScroll)
    },
    deactivated() {
      window.removeEventListener("scroll",this.handleScroll)
    },
    methods:{
      handleScroll: function () {
        const top = document.documentElement.scrollTop;
        if(top > 60){
          let opacity = top / 140;
          opacity = (opacity > 1) ? 1: opacity;
          this.opacityStyle = {opacity: opacity};
          this.showAbs = false
        }else{
          this.showAbs = true
        }
      }
    }
  }
</script>

<style lang="stylus" scoped>
  @import "~styles/varibles.styl"
  .header-abs
    position: absolute
    left: .2rem
    top: .2rem
    width: .8rem
    height: .8rem
    border-radius: .4rem
    background: rgba(0,0,0,0.8)
    line-height: .8rem
    text-align: center
    .header-abs-back
      color: #ffffff
      font-size: .4rem
  .header-fixed
    z-index: 2
    position: fixed
    top: 0
    left: 0
    right: 0
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #ffffff
</style>

